Refrigerator vents

Flathead · 06-01-2013, 02:59 PM

I took off the outside plastic vents today to add some screening material to keep out the bugs and noticed that the top vent had a piece of paneling on the interior covering the opening about two thirds of the way up from the bottom. There seemed to be a bit of heat in there from the refrigerator as it is operating. Has anyone noticed this on their 335SS, and has anyone given consideration as to cutting the paneling and allowing the bottom two vents on the cover to let more hot air out?

Dayle1 · 06-01-2013, 11:04 PM

I'm guessing that it is a baffle to force the air flow over the upper coils rather than allowing the air to flow around the coils. For proper operation you need a good 'chimney' effect and air flow over the coils. This is difficult to achieve when the upper vent is thru the slide-out wall rather than thru the roof. If you check the Dometic installation manual, it will give you a lot of info about this. Rear clearance must be 1 inch or less. Side clearance should be as close to zero as possible.

My frig. is set at an angle, so I added a baffle along one side to prevent air from rising along the side rather than thru the coils. Also, the rear clearance was more than 1 inch, so I added 3/4 inch board to reduce the clearance to meet Dometic's spec.

albertr · 06-02-2013, 02:15 AM

I have the same model 5th wheel as yours. Did you remove the fridge to do the work? Thks...Al

NorskeNY · 06-02-2013, 03:07 AM

Yours should have a fan mounted up in the top vent area too- it is like a PC fan - runs on 12VDC and cycles on when needed - ours has a high pitch sound. It draws air up the area to improve the cooling of the unit. The plywood pieces may help to direct the airflow past the cooling coils.

Take a look at this too:
http://bryantrv.com/docs2/docs/dometicventing.pdf

Found this on the internet - may add one to our unit.:
Adding fridge fansSo, I don't know whether to claim to be lazy or a
technophile, but having to mess with a switch to operate a fan to boost airflow
across the refrigerator's condensing coils seems to be one of those things I
would forget from day to day. I started looking around and found a
"thermistor controlled computer case fan". This fan is a Silenx
iXtrema Pro Thermistor Fan (Model XP7414T). The thermistor starts the fan at
70F (21C) at 24 cfm and as the temperature increases to 168F (75C), the airflow
increases to 72 cfm. This fan is also amazingly quiet! Thanks to Rick's
previous superior advice, I decided to mount this fan directly on the lower
outside louvered cover of the refrigerator such that it would push air into the
space below the condenser coils. I have a Dometic RM1350 refrigerator mounted
in the kitchen slide, and it does have a thermostat-controlled circulation fan
located about three-fourths of the way up to the upper louvered vent within the
condenser coil space.

I guess everyone knows that this August (2011) has been very
warm in north Texas. We have our Alpine parked under a shelter, so it is pretty
much in the shade until late evening. But with temperatures in the shade at
101F to 108F (38C – 42C), the refrigerator was working hard to keep the inside temperature
around 45F (7C), and if you opened the door, that quickly rose to 50F(10C)! And
what good is a refrigerator if you can't open the door for a beer! I installed
the thermistor fan and let it run for 24 hours before checking the temperature.
With all conditions the same (will it ever cool down in Texas?), the
refrigerator temperature dropped to 40F (4C)! Though I didn't time it, once the
door was opened, the recovery time seemed much quicker.

Edited by: NorskeNY

Flathead · 06-02-2013, 05:49 AM

Thank you for the responses
I am going to have to check to see if I have a fan, haven't heard one go on yet!
The info you gave on the fan install Bob is something I am definitely going to look into doing.
Al, no I did not remove the refrigerator, I was working from the outside and only removed the plastic vent covers from the outside of the rig.

NorskeNY · 06-02-2013, 06:43 AM

I ordered aSilenX Effizio Thermistor EFX-12-15T 120mm Case Fan from Newegg.com. It is not variable speed but is controlled by a thermistor. Not sure of I will mount it next to the one installed or in the bottom. The bottom may be a easier installation.

I order all of my computer parts from them. I usually purchase the parts and build my own computers.

Took some pictures - looks like it will be easy to install one next to the existing fan. The schematic shows that it is a 3 amp power fuse and thermal fuse - the thermal fuse may be the red item attached to the fins.

Area behind top cover:

<h1 style="padding: 0px; line-height: 1.1; letter-spacing: -1px; font-family: helvetica, arial, sans-serif;">Picture of fan behind panel - there are two spaces (pre-drilled holes to mount the fan) to install a fan - they chose the center . Fan is held in place by the two screws.</h1>

This may be what controls the fan - thermal fuse? The coil is what you see above the board in the fist picture.

Schematic and I think the in-line fuse for the fan

Edited by: NorskeNY

Livewire · 06-02-2013, 07:36 AM

The problem seems to be the side venting.The mechanic at my dealership added another fan but at the top vent and facing vent to exhaust more air.I have also considered buying another vent shield and altering it with screen to allow more movement of air when on site for camping only,not travel.

socoguy · 06-02-2013, 08:50 AM

As always Bob great info and Pics.

Flathead · 06-03-2013, 04:04 AM

Bob
Thank you for all the info!
Tony

NorskeNY · 06-03-2013, 05:53 AM

Did some more checking (retired so I have allot of time on my hands) - we have a Dometic model DM2852RBFX. On the label it has that the vent kit must be used (Vent Kit Form 321 32 38)

More info - vent kit

Where to purchase the complete kit:
http://www.shop.classarvrepairs.com/...3108705744.htm

Installation instructions (you may get an error message - click the closest match)
http://bryantrv.com/docs2/temp/powervent.pdf

Looks like the item attached to theRIGHT SIDE OF CONDENSER is the thermo switch. Closes
150 F/Opens 130 F<!--if gte mso 9>
<w:Word>
<w:View>Normal</w:View>
<w:Zoom>0</w:Zoom>
<w:TrackMoves/>
<w:Trackatting/>
<w:PunctuationKerning/>
<w:ValidateAgainstSchemas/>
<w:SaveIfInvalid>false</w:SaveIfInvalid>
<w:IgnoreMixed>false</w:IgnoreMixed>
<w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>
<w

onotPromoteQF/>
<w:LidThemeOther>EN-US</w:LidThemeOther>
<w:LidThemeAsian>X-NONE</w:LidThemeAsian>
<w:LidThemeComplex>X-NONE</w:LidThemeComplex>
<w:Compatibility>
<w:BreakWrappedTables/>
<w:SnapToGridInCell/>
<w:WrapTextWithPunct/>
<w:UseAsianBreakRules/>
<w

ontGrowAutofit/>
<w:SplitPgBreakAndark/>
<w:EnableKerning/>
<w

ontFlipMirrorIndents/>
<w:OverrideTableStyleHps/>
</w:Compatibility>
<m:mathPr>
<m:mathFont m:val="Cambria Math"/>
<m:brkBin m:val="before"/>
<m:brkBinSub m:val="&#45;-"/>
<m:smallFrac m:val="off"/>
<m:dispDef/>
<m:lMargin m:val="0"/>
<m:rMargin m:val="0"/>
<m:defJc m:val="centerGroup"/>
<m:wrapIndent m:val="1440"/>
<m:intLim m:val="subSup"/>
<m:naryLim m:val="undOvr"/>
</m:mathPr></w:Word>

http://www.americanrvcompany.com/Dom...per-Trailer-RV

Uses a 1 amp in-line fuse. Our schematic indicates it is a 3 amp in-line fuse.


Edited by: NorskeNY

Flathead · 06-03-2013, 12:10 PM

Thank you Bob. Now if it would stop raining for a bit here, I'll be able to go out and look at my set up a little closer!

NorskeNY · 06-05-2013, 03:10 AM

Fan came yesterday - temperature controlled and variable speed ,SilenX Effizio Thermistor EFX-12-15T. 

750 rpm at 68 deg F
1400 rpm at 176 deg F
12 Vdc
0.13 amp
1.56 watts
max air flow of 74 cfm

Tested the fan using of my computer extra 12 Vdc connections. Fan comes on at min speed when powered up. Putting the temp probe in a cup of hot water and the fan speeds up - can't even hear it. May wire it in series with the existing fan so it will still be controlled by the same thermal switch that the existing fan is powered from. That way it will not run all of the time - only when needed.

NorskeNY · 06-20-2013, 07:01 AM

Installed the 2nd fan today. I installed it in the top area below the Condenser<!--if gte mso 9>
<w:Word>
<w:View>Normal</w:View>
<w:Zoom>0</w:Zoom>
<w:TrackMoves/>
<w:Trackatting/>
<w:PunctuationKerning/>
<w:ValidateAgainstSchemas/>
<w:SaveIfInvalid>false</w:SaveIfInvalid>
<w:IgnoreMixed>false</w:IgnoreMixed>
<w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>
<w

onotPromoteQF/>
<w:LidThemeOther>EN-US</w:LidThemeOther>
<w:LidThemeAsian>X-NONE</w:LidThemeAsian>
<w:LidThemeComplex>X-NONE</w:LidThemeComplex>
<w:Compatibility>
<w:BreakWrappedTables/>
<w:SnapToGridInCell/>
<w:WrapTextWithPunct/>
<w:UseAsianBreakRules/>
<w

ontGrowAutofit/>
<w:SplitPgBreakAndark/>
<w:EnableKerning/>
<w

ontFlipMirrorIndents/>
<w:OverrideTableStyleHps/>
</w:Compatibility>
<m:mathPr>
<m:mathFont m:val="Cambria Math"/>
<m:brkBin m:val="before"/>
<m:brkBinSub m:val="&#45;-"/>
<m:smallFrac m:val="off"/>
<m:dispDef/>
<m:lMargin m:val="0"/>
<m:rMargin m:val="0"/>
<m:defJc m:val="centerGroup"/>
<m:wrapIndent m:val="1440"/>
<m:intLim m:val="subSup"/>
<m:naryLim m:val="undOvr"/>
</m:mathPr></w:Word>
 coil. I could not easily remove the wood sheeting in front of the present fan so I did not mount the new fan next to it (there are pre-drilled holes for mounting a second fan).

I installed the fan below the evaporator so there should be better cooling. It is held by 2 ty-wraps and the friction against the wall- it is pretty tight so it will not be moving around (The present fan is only held in place by two screws). I ran the wires down the right hand side of the rear of the refrigerator - pulled it as tight as I could against the wall to keep them away from the chimney. I took a switch off a failed computer power supply and used it for the on/off switch. I did not connect power to the light on the switch. I had a spare in line fuse holder with a 1 amp fuse so I used that for the connection to the 12VDC. The fuse holder for the present fan has a 3 amp fuse in it.Based upon the current draw of the new fan a 1 amp fuse will be do. I put the new fan sensor next to the evaporator coils - placed it away from the temperature switch for the present fan - may move it close to the switch.

The only negative thing about the installation is that I will need to turn the fan on/off when we have the refrigerator in use (and I am sure I will forget to turn it off some of the time when the camper is not in use).

One thing I noticed is that the wooden sheet that was installed to
direct the air flow of the present fan closes off the lower set of vents
on the upper cover so the new fan should improve the air flow out of
the Condenser<!--if gte mso 9>
<w:Word>
<w:View>Normal</w:View>
<w:Zoom>0</w:Zoom>
<w:TrackMoves/>
<w:Trackatting/>
<w:PunctuationKerning/>
<w:ValidateAgainstSchemas/>
<w:SaveIfInvalid>false</w:SaveIfInvalid>
<w:IgnoreMixed>false</w:IgnoreMixed>
<w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText>
<w

onotPromoteQF/>
<w:LidThemeOther>EN-US</w:LidThemeOther>
<w:LidThemeAsian>X-NONE</w:LidThemeAsian>
<w:LidThemeComplex>X-NONE</w:LidThemeComplex>
<w:Compatibility>
<w:BreakWrappedTables/>
<w:SnapToGridInCell/>
<w:WrapTextWithPunct/>
<w:UseAsianBreakRules/>
<w

ontGrowAutofit/>
<w:SplitPgBreakAndark/>
<w:EnableKerning/>
<w

ontFlipMirrorIndents/>
<w:OverrideTableStyleHps/>
</w:Compatibility>
<m:mathPr>
<m:mathFont m:val="Cambria Math"/>
<m:brkBin m:val="before"/>
<m:brkBinSub m:val="&#45;-"/>
<m:smallFrac m:val="off"/>
<m:dispDef/>
<m:lMargin m:val="0"/>
<m:rMargin m:val="0"/>
<m:defJc m:val="centerGroup"/>
<m:wrapIndent m:val="1440"/>
<m:intLim m:val="subSup"/>
<m:naryLim m:val="undOvr"/>
</m:mathPr></w:Word>
 area.

I'll do some temperature checks with and with out the fan in operation with a hand held IR temperature detector.

Did some checking on the present fan - it is a Sunon fan - PF92251B1-000U-A99. Found the data sheet on it:
4500RPM, 12VDC, 4.7-Watts, 0.393 amps, 75 cfm, Ball bearing(2), 47dB(A), Square - 92mm L x 92mm H x 25mm W.

Pictures of installation:

The present fan is below the new fan and to the left of it. I did not want to install this one in the "direct' air flow of the present fan.

Edited by: NorskeNY

NorskeNY · 06-21-2013, 07:57 AM

Turned on the fridge - seems to cool down faster. After 2 hours the walls of the freezer were 5 degrees. The fins in the fridge were 55 degrees. Inside wall temp is 67 degrees.

Outside air temp is 81 degrees and the side of the trailer is in the shade.

Checked some temps and the upper area was about 110 degrees. The original fan was running - after the upper vent cover was off for about 5 minutes the area cooled off and the original vent fan turned off. Put the cover on again and in 10 minutes it turn back on - with the new fan running too.

The line coming up to the condenser coil was 138 degrees. The fins on the condenser ranged from 105 to 110 degrees. Now I see why an external fan is needed for RVs with refrigerator in the slide.

Just purchased a battery operated fan to move air around inside the refrigerator. I'll see how that helps to cool down the refrigerator and maintain temp when in use,

Edited by: NorskeNY

TosorontioWanderers · 07-09-2013, 08:10 AM

We have a 2012 335SS and on our maiden voyage to Florida I found the piece of paneling you're talking about and cut it out thinking it might help with the cooling.
Upon returning home and taking it to the dealer, they re-installed the piece I cut out and the technician showed me the manual that shows it must be in there. It is there for a chimney effect and is intentional.
Although the fan is noisy it seems to do the trick. We have had the unit running with temps in the 90's and the fridge works fine, although the fan noise can be bothersome.

NorskeNY · 07-10-2013, 01:56 AM

I think the "baffle" helps to direct the air flow from the fan up to the condenser. When I had only the original fan running it did a pretty good job directing the air flow to the condenser.

We got used to the fan noise - seems one could find a fan that is not so noisy.

I think the fridge cools down faster and stays cooler with the extra fan. But our unit was in the shade when we went camping - was 90 degrees out. Both fans ran most of the time.

You may also like: